424mkIII - Problems with Track 4

Hi all. I’ve recently been digitally archiving my old 4-track master tapes from the mid-late 90s, and I’ve run into a bit of a pickle.

I’ve noticed that for many of the tapes, the fourth track sounds thin and hissy, with greatly diminished low end. At first I assumed that the tapes themselves were simply deteriorating with age, but
when I play these tapes in reverse, the same track (now track 1) sounds nice and full. What’s particularly puzzling is that I have a handful of tapes that don’t suffer from this problem at all.

My 4-track machine is a Tascam 424mkIII, and I’m transferring to Pro Tools via the tape outs. I’ve tried using the effects sends for track 4 to see if that made any difference, but it sounds the same as the tape out.

I borrowed a friend’s 424mkIII hoping that maybe it was just my machine, but I ran into the same problem.

Well that is a Pickle all right. I would see if the sound is like that on other machines like the 234 but it might be that noise reduction was involved and not used at this point. This needs to be looked at.
Another question to me on a 8 track reel had a lack of signal and higher noise. Cleaning the tape path resolved the problem. You can look at a tape and see if there is damage or not. This wear or damage is usually affecting the high end rather than all levels. Maybe the head preamp has some bad parts in it. I can not say exactly what the problem is without an inspection of the items of subject. Anything made a while back and for profit purposes especially in the cassette market can have some poor grade parts in them. I have found failed 10V capacitors even in the Teac Z7000 named Marcon. Any time I see them out they go. 10V caps which might be in your preamp have a very high failure rate. I would replace them with a high grade Nichicon or Panasonic FM or FC cap which will be much better performance and longevity wise.